1. Field of the Invention
The present invention relates generally to a wireless charging network, and more particularly, to a method and apparatus for controlling an abnormal status of a wireless power receiver such as over-temperature, overvoltage, overcurrent, and the like.
2. Description of the Related Art
A mobile terminal such as a portable phone, a Personal Digital Assistant (PDA), and the like is driven with rechargeable batteries due to their nature, and the battery of the mobile terminal is charged through supplied electric energy by using a separate charging device. Typically, the charging device and the battery have separate contact terminals at an exterior thereof, respectively, and are electrically connected with each other by contacting the contact terminals.
However, since the contact terminal protrudes outwardly in such a contact type charging scheme, the contact terminal is easily contaminated by foreign substances and thus the battery charging may not be correctly performed. Further, the battery charging may also not be correctly performed in a case where the contact terminal is exposed to moisture.
Recently, a wireless charging or a non-contact charging technology has been developed and is used for electronic devices to solve the above-mentioned problem.
Such a wireless charging technology employs wireless electric power transmission/reception, and corresponds to, for example, a system in which a battery can be automatically charged when a portable phone is not connected to a separate charging connector but merely placed on a charging pad.
Wireless electric toothbrushes or a wireless electric shavers use wireless charging technology. Accordingly, a waterproof function can be improved since electronic products are wirelessly charged through the wireless charging technology, and the portability of electronic devices can be increased since there is no need to provide a wired charging device. Technologies related to the wireless charging technology are expected to be significantly developed in the coming age of electric cars.
The wireless charging technology largely includes an electromagnetic induction scheme using a coil, a resonance scheme using a resonance, and an RF/microwave radiation scheme converting electrical energy to a microwave and then transmitting the microwave.
Up to now the electromagnetic induction scheme is mainstream, but it is expected that the day will come when all electronic products are wirelessly charged, anytime and anywhere, without a wire in the near future on the strength of recent successful experiments for wirelessly transmitting power to a destination spaced away by dozens of meters through the use of microwaves at home and abroad.
A power transmission method through the electromagnetic induction corresponds to a scheme of transmitting electric power between a first coil and a second coil. When a magnet is moved in a coil, induction current is generated. By using the induction current, a magnetic field is generated at a transmission side, and electric current is induced according to a change of the magnetic field so as to make energy at a reception side. The phenomenon is referred to as magnetic induction, and the electric power transmission method using magnetic induction has high energy transmission efficiency.
With respect to the resonance scheme, electricity is wirelessly transferred using an electric power transmission principle of the resonance scheme even if a device to be charged is separated from a charging device by several meters. The wireless charging system uses an electromagnetic wave containing electrical energy which resonates instead of making sounds resonate. The resonated electric energy is directly transferred only when there is a device having a resonance frequency and parts of electric energy which are not used are reabsorbed into an electromagnetic field instead of being spread in the air, so that it is considered that the electric energy does not affect surrounding machines or people unlike other electromagnetic waves.
Meanwhile, active research on a wireless charging scheme is currently being progressed, but standards for a wireless charging order, a search for a wireless power transmitter/receiver, selection of a communication frequency between the wireless power transmitter/receiver, a wireless power control, selection of a matching circuit, and communication time distribution to each wireless power receiver in one charging cycle have not been proposed.
Particularly, in the case where the wireless power transmitter charges at least one wireless power receiver, development in technology of charging a new wireless power receiver to be charged has been required.